In patent literature, several compositions are disclosed which include various combinations of alkali silicates, other silicates, oxides, phosphates, and chlorides.
U.S. Pat. No. 1,762,911 relates to the manufacture of a material for sealing fireworks which comprises a mixture of approximately 50% waterglass, approximately 10% metal oxide, and approximately 40% aluminium silicate or kaolin. This patent contains no disclosure of qualities which are relevant to the present invention, but is basic for later applications of oxide-alkali silicate compounds.
U.S. Pat. No. 1,757,470 relates to the manufacture of a fireproof and heat insulating material which, in addition to the mentioned and known oxide-alkali silicate compounds, comprises waste products from the manufacture of various soda compounds which are essentially calcium compounds. Fire preventing and heat insulating qualities are probable, but are not documented in the specification.
U.S. Pat. No. 3,707,396 relates to the manufacture of an impregnating agent/binder consisting of 100 parts by weight of alkali silicate, 135 parts by weight of a finely divided material from the group comprising silicium, ferro-silicium, copper-silicium, calcium-silicium compounds and mixtures of the same with 1-25 parts by weight of a finely divided oxymetal compound with grain size below 100 microns and a smooth surface.
This patent, thus, essentially relates to combinations of silicium metal compounds and oxymetal compounds and the effect of such compounds on alkali silicate bonds due to the fact that the added silicon compounds are transformed into SiO.sub.2 and form insoluble alkali metal/silicate compounds. According to the specification, optimal effects are achieved with defined and relatively fine grain sizes both with regard to the silicon compounds and metal oxides of interest. There is reason to suppose that the alkali silicate-metal oxide reactions are decisive with regard to the water resistance of the reaction product, whereas the silicon metal compounds are believed to improve the mechanical qualities and to influence remaining resistance qualities, even though this does not appear in the specification.
European patent application 0,001,091 relates to the manufacture of a prepolymer based on alkali silicate and metal oxides which are, via a preliminary reaction and step-wise drying/condensation, transformed into a material which is suitable for shaping and pressing.
European patent application 0,240,940 relates to a composition for the manufacture of a hydrophilous film forming coating on aluminium and which comprises an alkali silicate, an inorganic accelerator, and a water soluble organic mixture of high molecular weight. The inorganic accelerator consists of a mixture comprising aluminium phosphate, magnesium phosphate, trivalent phosphoric acid, magnesium oxide, zinc oxide, and carbonates, sulphates, sulphites or chlorides of polyvalent metals. The application essentially relates to combinations of alkali silicates, inorganic accelerators on the mentioned basis, and said organic mixtures.
U.S. Pat. No. 4,762,753 relates to a mixture which acts as a foundation for a surface coating and consists essentially of an aqueous solution with 4-16% by weight of solids, 24-38% by weight of alkali silicate, 18-28% of magnesium oxide, magnesium hydroxide or mixtures of the same, 7-19% of titanium oxide, and 22-53% of mica. The coating is suitable for forming an electrically insulating coating on metal products.
U.S. Pat. No. 4,789,652 relates to a fireproof material for lining melting furnaces which contains fireproof basic materials including overburned magnesite, called "magnesia clinker". Overburned magnesite is produced at temperatures of 1600.degree.-1700.degree. C. and is distinguished by its excellent resistance against high temperatures. The material has no reactive power, in contrast to magnesium oxide which is manufactured by calcination in the temperature region of 800.degree.-900.degree. C.
The reactive qualities of calcinated magnesium oxide are desirable both with regard to its strength and degree of water resistance. Overburned magnesite in the form of magnesia clinker does not contribute to any of these qualities, but it shows considerably better qualities in case of high temperature loads than does calcinated magnesium oxide.